pub fn cartesian(dims: &[Dim]) -> Vec<HashMap<String, Value>>Expand description
Build the cartesian product of the dimensions as per-tuple interpolation
contexts. Each context maps dim_id -> { alias: value }, so a token
${dim_id.alias} resolves to that tuple’s value via the same
interpolate_record path the parent/child matrix uses. An empty dimension
yields no tuples. Pure.